The present invention relates to a cooking apparatus which is of particular advantage for high output processing of food.
There is a requirement for cooking apparatus which can cook high volumes of food items in a time and energy efficient manner. Therefore, it is most important that the cooking medium be used as sparingly as possible to reduce heating and other running costs. This problem is particularly acute in the case of cooking media such as vegetable oil, animal fat, shortening and the like, which also readily oxidise if overheated. This results in wastage of cooking medium and poor food quality.
Further, oxidation of cooking media is a problem that still requires attention by manufacturers of cooking apparatus. The problem primarily arises from two sources; firmly, inadequate cooking medium temperature control and, secondly, continued usage of cooking apparatus in which the cooking chamber is exposed to air.
Exemplary of an apparatus having the aforementioned disadvantages is British Patent No. 621821 (Crittall) which cooks food by low pressure spraying of cooking medium onto food items and provides the heater means for the cooking medium in complete isolation to the cooking apparatus. Further, the heater means or calorifier is in the form of a heated sump or tank-like reservoir. Thus heat loss problems are caused by heat loss from the calorifier, which requires high energy inputs to overcome the isolation thereof from the cooking apparatus. Moreover, sumps having a high volume have been found by the present inventor to require longer residence times for efficient heating of the cooking medium. On the other hand, smaller volumes expose the cooking medium to overheating, consequential wastage and undesirable oxidation.
Further, if the cooking medium is a solid fat, serious problems of congelation may well be found to occur in the calorifier and the pipes leading from the calorifier to the cooking chamber, the more so because the spraying of cooking media occurs at low pressure.
Any attempt to overcome these problems at the calorifier by high energy inputs is likely to result in unacceptable temperature over-runs in the cooking medium leading to burning of food items, oxidation of the cooking medium and consequential undesirable food taste and odour quite apart from the added energy costs.
U.S. Pat. No. 4,047,476 relates to an improvement to the Crittall cooking apparatus which employs high pressure sprays. This may lead to better heat exchange in the cooking operation but heating of the cooking medium still occurs in a cooking medium sump with the problems this entails in terms of high energy input, uneven heating of the cooking medium and oxidation thereof. Therefore, this proposal does not address some of the most critical problems of the Crittall apparatus.